This invention relates generally to irrigation water sprinklers of the type having a sprinkler spray head or nozzle for rotating one or more outwardly projected water streams through a prescribed arcuate spray path. More particularly, this invention relates to an improved irrigation sprinkler having an improved spray head and improved rotary drive means designed for self-flushing operation to prevent accumulation of water-entrained grit and other particles which could otherwise impair performance reliability and consistency.
Irrigation sprinklers are well known of the general type designed to provide one or more outwardly projected streams of irrigation water. Such irrigation sprinklers traditionally include a sprinkler body having one or more spray nozzles mounted thereon, wherein the sprinkler body is rotatable for sweeping the discharged water stream or streams through a prescribed arcuate spray path, such as a quarter-circle, half-circle or full-circle path, to irrigate surrounding vegetation. In this regard, the sprinkler further includes a rotary drive mechanism, for example, an impact or reaction drive mechanism which is water-driven to rotate the sprinkler body over the prescribed spray path. Other types of rotary drive mechanisms include water-driven turbines and drive balls for rotating at least the portion of the sprinkler body carrying the spray nozzle resulting in water distribution over the desired terrain area.
In some specialized irrigation applications, it is desirable to deliver irrigation water to surrounding terrain at a relatively low precipitation rate primarily to avoid excess water run-off and waste. In addition, it is sometimes desirable to provide such low precipitation rates by use of a relatively small number of irrigation sprinkler devices to correspondingly minimize system cost and complexity including, for example, the required number of sprinkler heads and related piping and controls. To this end, rotating stream sprinklers have been developed to provide one or more discrete water streams which are projected outwardly with substantial range but at a relatively low flow rate. Such sprinklers have normally included internal drive mechanisms for rotating the water streams continuously or in a succession of small rotational steps at a relatively slow angular velocity to sweep the projected water stream or streams through the prescribed part-circle or full-circle spray path. In rotating stream sprinklers of this type, the drive mechanisms traditionally have comprised turbine drive, ball drive, and/or gear drive components which, unfortunately, have been designed and assembled in a manner rendering the drive mechanism unduly susceptible to jamming upon accumulation of small grit and other particles in and about the moving components. As a result, such rotating stream sprinklers have experienced inconsistent and/or unreliable operating performance due to the presence of significant quantities of grit in most water supply systems. Accordingly, to insure reliable operation of the sprinkler, it has been necessary to provide significant water filtering capability, resulting in undesirable increases in irrigation system cost and complexity.
There exists, therefore, a significant need for an improved irrigation sprinkler of the type providing one or more outwardly projected discrete water streams swept through an arcuate spray path of predetermined size, wherein the improved sprinkler is designed for effective self-flushing operation of internal drive and nozzle components to prevent grit accumulation and accompanying performance impairment. The present invention fulfills these needs and provides further related advantages.